Method of and means for preventing leakage



March 20, 1928. 1,663,035

D. F.. ASBURY METHOD OF AND MEANS FOR PREVENTING LEAKAGE Filed Feb. 19, 1925 2 Sheets-Sheet 1 i l x l T f M? l /7 go i L) l Z2 v 5 #4 g 75/ /5 r dffly zsi I @bbom' March 20, 1928. 1,663,035

D. F. ASBURY METHOD OF AND MEANS FOR PREVENTING LEAKAGE Filed Feb. 19. 1925 2 Sheets-Sheet 2 ADJZIfls-ar A Patented Mar. 20, 1928;

DORSEY F. ASBURY, OF BECOMES ISLAND, MARYLAND.

' METHOD O AND'MEANS F eae e ifla l Application filed February My invention relates to a method of and means for preventing leakage of fluid past a member movable in a passageway between high and low pressure fluid chambers, to which end it consists in the various improvements over existing methods and means for the same purpose as will be more fully described hereinafter in connection with the accompanying drawings and particularly defined in the appended claims.

In the drawings, wherein like charactersof reference denote corresponding parts in the different v1ews:

Fig. 1 is a vertical section through a. por- I tion of an internal combustion engine shoving one status of a means'for accompl sh ng my purpose; and V Fig. 2, a View similar to Fig. 1 showing another status of the means for accomplishing my purpose, r

. By reference to the drawings it will be observed that I have illustrated an internal combustion engine equipped with a valve mechanism of the same general type constitutingthe subject matter of my prior Patent 1,388,520, and that I haveshown my present invention in one instance as designed .to prevent leakage of relatively high pressure exhaust gases past the barrel or pistonva lve of such mechanism into the relatively low pressure intake gases, and in another instance as designed to prevent leakage of relatively high pressure gases of explosion past the piston of the engine into thesbase thereof which is subject to relative slow pressure. I desire to point out, however, that these disclosures are merely-for the purpose of illustrating specific utilitites of my invention and should so beconstrued, as manifestly the invention may be found to be equally'useful in other.mechanis1ns presenting substantially the same problems with respect to the prevention of leakage of fluids as are encounteredin vthe internal combustion engine art in the particular instancesment-ione'd. f

The engine illustrated is of the valve-inhead type and includes essentially alcylinder 10, a piston 11, reciprocal therein, a passage or chamber 12 for the admission of intake gases, a passage or chamber 13 for carrying off exhaust gases, and a passageway 14, bet-weensaid passage or' chambers 12 and 13, within which is arranged a valvemechanism for controlling the intakeand exhaust 19, 1925. Serial No. 10,233.

ofgases through a port 15 to and from the cylinder 10.

Asmy aforesaid prior Patent 1,388,52 fully describes the essential structural characteristics and mode "of operationbf the valve mechanism herein illustrated,"it is seats against the inner end ofbarrel or piston valve '16 to prevent exhaust gasesfroni traveling through the latter into'the' intake passage or chan'iber 12, and this valve' a'lso operates to control the intake of gases from passage or chamber 12 into the cylinder 10', Y i

all as is well known. Thus it is evident that during exhaust the inner end of the barrel or piston valve is subjected to' the relatively,80

high pressure of the exhaust gases present "in passageo'rchamber 13, while theouterend thereof is subjected onlyto the relatively low pressure of the intake gases present in pas sage or chamber 12, and under such conditions there is a very pronounced tendencyoif;

the high pressure exhaust asesto-f leak from passage or chamber 13 past the barrel'or piston valve into the intake'passag'e or chamber 12 due to the'difierence in pressure"exis'tirig in said chambers; To prevent such" leakage I form the outer end of the "barrel'or "piston valve 16, that is, the end'thereodf which-"is subjected to the low pressure intake gases, as the male element of a clash-potand arrange within the passage way 14 a member 20 formed as the female-element ofsaid dash pot, thearrangm'ent being suchthat when the barrel or piston valve'is closed, that is',-"a-'t its limit of inward-movement,'as shown in Fig. 1, the male element of said-dash pot *is disposedout of the female elementso that in take gases may fill the -latter,while on the otherhand, when the barrelor piston valve is opened by-theinfiuence of the pressure and velocity ofexhaust gases, the male dash p'ot element is moved, into the female element with the result that the intake gases therein are compressed. Around the outside of'the' barrel or piston valve 16, intermediateits ends, is formed an: annular recess 21', While in the wall defining passageway 14 is formed one or more grooves 22 leading from the bottomof the female dash pot element inward towards the barrel or piston valve 16, said groove or grooves being'of such length as to be overlapped by. the annular recesss 21 when the male dash pot element has'almost reached the bottom of the female dash pot element, sothat the intake gases compressed pressure exhaust gases topass by the barrel r in said; dash pot are forced under relatively. high pressure into said annular recess Where they'act to balance the tendency of the high or pistonv valve into the intake passage or chamber, and where they-are trapped due to blanking of said annular recess and said grooves when the male element is moved outward with respect to the female element by the spring 17 as-the exhaust pressure vanishes, so as to act to balance the initial tendency of the exhaust gases to leak past'the barrel or piston valve into the intake passage when exhaust again takes place.

To prevent leakage of relatively high pressure gases of explosion within cylinder 10 past piston 11 into the base of the engine which is subject to relatively low pressure, I utilize substantially the same method and v'means described in connection with valve16 that is, I form the open end of the piston as the female element of a dash pot and arranged within the cylinder, for cooperation with said female element, a male element 23, while in the Wall of the piston I form an annular recess 24: and provide in the wall of the cylinder a groove or grooves 25-of such length of the female element.

as to overlap-said recess when the male dash pot element has almost reached the bottom between this arrangement and the arrangement described in connection with barrel or piston valve 16 is that, in the first instance the piston carries the male element of the dash pot while in,the second instance the piston carries the female element of the dash pot. However, the mode of operation and the results achieved are the same in each instance: As the piston nears the completion of its'down stroke the female element cooperates with the .male element ofthe dash pot to compress a portion of the low pressure.

fluid in the base of the engine and'force it under high pressure through the groove or grooves 25 into recess 24 where it acts to balance thetendency of the'high pressure ex plosive gases above the piston to passby the latter into the base. Upon upward move-' ment of the piston the gases under high pres sure are trapped inthe recess to balance the tendency of the initial high pressure gases above the piston to escape past the latter when the next explosion occurs in the cylinder. 1 7

It will be observed that the fluid entering the recesses .Zla'nd 24 serves to lubricate the The only differencesliding surfaces ofthe barrelv valve 16 and piston 11, respectively, aswell as the walls of engine with which they engage; also that the dash pots serve to cushion movement of both thebarrel valve'and piston in one direction, and that said dash pots are self cleaning due to the inclination of the bottom of the female element in one instance and to the inclination ofthe end of the male element in the other instance. Itwill further be apparent that instead of forming the recesses 21, 24 in the piston elements they might readily beformed inthe wallssurrounding the piston element should such an I the high pressure fluid chamber to balance the tendency of 'fiuid'in the high pressure chamber to pass by said member into the lowpressure chamber.

2. In mechanism of the class described,

a cylinder between high and low pressure fluid chambers, a reciprocal piston slidable in said cylinder, means defining a' cavity opening to the sliding .faces' of the cylinder and piston, a dash pot within which a portion of the fluid in the low-pressure chamber is adapted to. be compressed by movement of said piston to cushion the latter, and means placing said dash pot in communication with said cavity as the piston approachesthe end of its stroke in onedirec tion to reduce the pressure in said dash pot, said means operating to cut off .such communication when the piston is moved a pre- 7 determined distance in the other direction whereby the pressure. in saidrcavity is re tained therein to balancethe tendency of fluid in the high pressure chambervto pass by said piston into the low pressure chamber. V

3. In mechanism of the class described,a cylinder, a piston reciprocable in said 'cyla inder, and a dash pot within which fluid is adapted to be compressed by movement of i said piston to cushion the same, said dash, pot including a chamber element and a plunger element movablejinto and out of the same the end of-said plunger element being inclined whereby matter will slideofl .the same when it is out of the chamber member. 7

4. In mechanism of the class described, a cylinder, a piston slidable therein, a dash pot plunger element carried by said piston and a dash pot chamber element with which said plunger element cooperates to cushion movement of said piston, means defining a cavity opening to the sliding faces of the cylinder and piston intermediate the ends of the latter in any position thereof within the cylinder, and means defining a by-pass constantly in communication with said dash pot and cut ofl' from and placed in communication with said cavity by movements of said piston.

5. Means to prevent leakage of fluid past a member reciprocal in a passageway be tween high and low pressure fluid chambers comprising a dash pot composed of cooperating male and female elements one of which is carried by said member and the other of which has a fixed location within the low pressure chamber, said elements being arranged with respect to one another so that movement of said reciprocal member in the direction of the low pressure chamber will cause them to coact to compress a portion of the fluid in sa1d low pressure chamber, and

7 means whereby the low pressure fluid compressed by said dash pot elements is caused to balance the tendency of fluid in the high pressure chamber to escape past said reciprocal member into the low pressure chamber.

ment of said member in the direction of said low pressure chamber causes said dash pot to exert a compressive action on fluid contained therein, and means whereby the fluid compressed by said dash pot is caused to balance the tendency of fluid in said high pressure chamber to escape past said reciprocal member into said low pressure chamber.

7. In mechanism of the class described, a cylinder between high and low pressure fluid chambers, a reciprocal piston slidable within said cylinder, means defining a cavity opening to the sliding faces of said cylinder and piston, means operated by movement of said piston to compress a portion of the fluid in said low pressure fluid chamber, and means whereby the fluid compressed by said compressing means is conducted to said cavity to balance the tendency of fluid in the high pressure chamber to escape past said piston into the low pressure chamber. In testimony whereof I hereunto afix m signature.

DORSEY F. ASBURY. 

